Das Chinmoy, Nishiguchi Taichi, Fan Zeyu, Horike Satoshi
Institute for Integrated Cell-Material Sciences, Institute for Advanced Study, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto606-8501, Japan.
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto615-8510, Japan.
Nano Lett. 2022 Dec 14;22(23):9372-9379. doi: 10.1021/acs.nanolett.2c03207. Epub 2022 Nov 28.
We investigated a mechanism of crystal melting and crystallization behavior of a two-dimensional coordination polymer [Ag(L1)(CFSO)] (, L1 = 4,4'-biphenyldicarbonitrile) upon heating-cooling processes. The crystal showed melting at 282 °C, and the following gentle cooling induced the abrupt crystallization at 242 °C confirmed by DSC. A temperature-dependent structural change has been discussed through calorimetric, spectroscopic, and mechanical measurements. They indicated that the coordination-bond networks are partially retained in the melt state, but the melt showed a significantly low viscosity of 9.8 × 10 Pa·s at which is six orders lower than that of ZIF-62 at (435 °C). Rheological studies provided an understanding of the fast relaxation dynamics for the recrystallization process, along with that the high provides enough thermal energy to crossover the activation energy barrier for the nucleation. The isothermal crystallization kinetics through calorimetric measurements with applying the Avrami equation identified the nature of the nuclei and its crystal growth mechanism.
我们研究了二维配位聚合物[Ag(L1)(CFSO)](L1 = 4,4'-联苯二甲腈)在加热-冷却过程中的晶体熔化和结晶行为机制。该晶体在282℃时熔化,随后的缓慢冷却导致在242℃时突然结晶,这通过差示扫描量热法(DSC)得到证实。通过量热、光谱和力学测量讨论了随温度变化的结构变化。结果表明,配位键网络在熔融状态下部分保留,但熔体在282℃时显示出极低的粘度,为9.8×10 Pa·s,比ZIF-62在435℃时的粘度低六个数量级。流变学研究有助于理解再结晶过程的快速弛豫动力学,同时高温提供了足够的热能以跨越成核的活化能垒。通过应用阿弗拉米方程进行量热测量的等温结晶动力学确定了晶核的性质及其晶体生长机制。